Find the second largest numberΒΆ

Find the second largest number in a list.
def second_largest(numbers):

    if len(L) < 2:
        return

    if len(L) == 2 and L[0] == L[1]:
        return

    dup_items = set()
    uniq_items = []

    for x in L:
        if x not in dup_items:
            uniq_items.append(x)
            dup_items.add(x)

    uniq_items.sort()

    return  uniq_items[-2]

# test
print(second_largest([1,2,3,4,4]))                   # 3
print(second_largest([1, 1, 1, 0, 0, 0, 2, -2, -2])) # 1
print(second_largest([2,2]))                         # None
print(second_largest([1]))                           # None